1. Field of the Invention
The present invention relates to a light source device and an image forming apparatus.
2. Description of the Related Art
In recent years, in an image forming apparatus such as a laser printer and a digital copying machine, there is an increasing demand for high-speed and high-density printing. As one measure for meeting the demand, a technology has been proposed in which an optical scanning device that includes a light source having a plurality of light emitting units is used to scan a scanning surface with a plurality of light fluxes.
A semiconductor laser is generally employed as a light source, and recently, a vertical cavity surface emitting laser (hereinafter, “VCSEL”) has been used in addition to an edge emitting semiconductor laser that was used more commonly.
The VCSEL light source is generally constructed of a VCSEL element and a package on which the VCSEL element is mounted. The VCSEL element is sealed in by using a lid (a package lid) made of a translucent material such as a glass or a sapphire in order to ensure environmental resistance (protection against dust or dirt) (see, for example, Japanese Patent Application Laid-open No. 2001-267681).
However, the package lid reflects a light even though it has a high translucency. Furthermore, a distance between the VCSEL element and the package lid is so close that when image formation is performed by using the VCSEL light source, the reflected light from the package lid returns to the VCSEL, resulting in what is called optical feedback which causes negative impact.